Simultaneous Measurement of Fuel Droplet Deposition Amount and Oil Film Thickness on Spray Impingement Using Double Laser Induced Fluorescence Method 2017-01-2371

Diesel Particulate filter (DPF) is installed as after treatment device of exhaust gas in diesel engine, and collects the Particulate Matter (PM). However, as the operation time of engine increases, PM is accumulated in the DPF, resulting in deterioration of PM collection efficiency and increasing in pressure loss. Therefore, Post injection has been attracted attention as DPF regeneration method for burning and removing PM in DPF. However, Post injection causes oil dilution when fuel is injected at the middle to late stage of expansion stroke. Oil dilution are concerned to deteriorate the sliding property of piston and the thermal efficiency. For this reason, it is necessary to elucidate the mechanism and the behavior that spray impinges lubricating oil film. Therefore, in this study, we aimed to construct model of Computational Fluid Dynamics (CFD) that predicts amount of oil dilution which is concern for post injection in diesel engine, with high accuracy. In this report, we constructed Double Laser Induced Fluorescence (DLIF) applying LIF. In the DLIF, two kinds of fluorescent dyes were dissolved to diesel fuel and engine oil respectively, and Ultraviolet (UV) -LED was used as excitation light. Each fluorescence wavelength was spectrally separated at a specific wavelength. DLIF makes it possible to simultaneously and continuously measure fuel film thickness and oil film thickness in the case of diesel spray impinging lubricating oil film. As the result of measurement using DLIF, it was found that a large difference of deposition amount which fuel spray impinges dry wall and lubricating oil film. Due to influence of lubricating oil film, deposition area and deposition amount decreases compared with dry wall.